SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '571b90df316763e3a420f6f7c4cb865e462274cec16385500f0d24109d7b53f3' 
  AND token = 'vOkxSPbmsGmCsntM19QzVgUDRkHKJmfy03FOxMBp+dc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}